Mast cells and amines in normal ocular tissues.

Mast cells in the lid and uvea of the rat, guinea pig, rabbit, and monkey were counted by averaging the counts in serial histologic sections and multiplying by an appropriate calculated geometric factor. The lid counts are higher than the uveal counts and the iris count is low compared with the remainder of the uvea. Histamine and serotonin contents xoere determined by biochemical assay. The uveal histamine values vary from 1.2 to 8.9 (ig per gram, and the lid values vary from 11 to 105 fig per gram. The uveal values are at least 10 to 100 times the normal aqueous concentrations of histamine in the literature. Mast cells contain from 1 to 8 fifig of histamine per cell ivith the exception of the anterior uveal tissues of the rat and rabbit where the histamine—mast cell ratio is one hundred fold higher. The serotonin values of uvea and lid range from 0.3 to 4.2 fig per gram. Mast cells contain from 0.06 to 0.20 HHg of serotonin per mast cell with the exception of the uveal tissues of the rat and rabbit in which the serotonin mast cell count is twentyfold higher.